On Tue, May 25, 2021 at 03:22:53PM +0530, Anshuman Khandual wrote: > > > On 5/25/21 12:02 PM, Mike Rapoport wrote: > > On Tue, May 25, 2021 at 11:30:15AM +0530, Anshuman Khandual wrote: > >> > >> On 5/24/21 12:22 PM, Mike Rapoport wrote: > >>> Hello Anshuman, > >>> > >>> On Mon, May 24, 2021 at 10:28:32AM +0530, Anshuman Khandual wrote: > >>>> > >>>> On 4/22/21 1:20 PM, Anshuman Khandual wrote: > >>>>> Platforms like arm and arm64 have redefined pfn_valid() because their early > >>>>> memory sections might have contained memmap holes after freeing parts of it > >>>>> during boot, which should be skipped while validating a pfn for struct page > >>>>> backing. This scenario on certain platforms where memmap is not continuous, > >>>>> could be captured with a new option CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES. > >>>>> Then the generic pfn_valid() can be improved to accommodate such platforms. > >>>>> This reduces overall code footprint and also improves maintainability. > >>>>> > >>>>> free_unused_memmap() and pfn_to_online_page() have been updated to include > >>>>> such cases. This also exports memblock_is_memory() for all drivers that use > >>>>> pfn_valid() but lack required visibility. After the new config is in place, > >>>>> drop CONFIG_HAVE_ARCH_PFN_VALID from arm64 platforms. > >>>>> > >>>>> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> > >>>>> Cc: Will Deacon <will@xxxxxxxxxx> > >>>>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > >>>>> Cc: Mike Rapoport <rppt@xxxxxxxxxx> > >>>>> Cc: David Hildenbrand <david@xxxxxxxxxx> > >>>>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > >>>>> Cc: linux-kernel@xxxxxxxxxxxxxxx > >>>>> Cc: linux-mm@xxxxxxxxx > >>>>> Suggested-by: David Hildenbrand <david@xxxxxxxxxx> > >>>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> > >>>>> --- > >>>>> This patch applies on the latest mainline kernel after Mike's series > >>>>> regarding arm64 based pfn_valid(). > >>>>> > >>>>> https://lore.kernel.org/linux-mm/20210422061902.21614-1-rppt@xxxxxxxxxx/T/#t > >>>>> > >>>>> Changes in RFC V2: > >>>>> > >>>>> - Dropped support for arm (32 bit) > >>>>> - Replaced memblock_is_map_memory() check with memblock_is_memory() > >>>>> - MEMBLOCK_NOMAP memory are no longer skipped for pfn_valid() > >>>>> - Updated pfn_to_online_page() per David > >>>>> - Updated free_unused_memmap() to preserve existing semantics per Mike > >>>>> - Exported memblock_is_memory() instead of memblock_is_map_memory() > >>>>> > >>>>> Changes in RFC V1: > >>>>> > >>>>> - https://patchwork.kernel.org/project/linux-mm/patch/1615174073-10520-1-git-send-email-anshuman.khandual@xxxxxxx/ > >>>>> > >>>>> arch/arm64/Kconfig | 2 +- > >>>>> arch/arm64/include/asm/page.h | 1 - > >>>>> arch/arm64/mm/init.c | 41 ----------------------------------- > >>>>> include/linux/mmzone.h | 18 ++++++++++++++- > >>>>> mm/Kconfig | 9 ++++++++ > >>>>> mm/memblock.c | 8 +++++-- > >>>>> mm/memory_hotplug.c | 5 +++++ > >>>>> 7 files changed, 38 insertions(+), 46 deletions(-) > >>>>> > >>>>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > >>>>> index b4a9b493ce72..4cdc3570ffa9 100644 > >>>>> --- a/arch/arm64/Kconfig > >>>>> +++ b/arch/arm64/Kconfig > >>>>> @@ -144,7 +144,6 @@ config ARM64 > >>>>> select HAVE_ARCH_KGDB > >>>>> select HAVE_ARCH_MMAP_RND_BITS > >>>>> select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > >>>>> - select HAVE_ARCH_PFN_VALID > >>>>> select HAVE_ARCH_PREL32_RELOCATIONS > >>>>> select HAVE_ARCH_SECCOMP_FILTER > >>>>> select HAVE_ARCH_STACKLEAK > >>>>> @@ -167,6 +166,7 @@ config ARM64 > >>>>> if $(cc-option,-fpatchable-function-entry=2) > >>>>> select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \ > >>>>> if DYNAMIC_FTRACE_WITH_REGS > >>>>> + select HAVE_EARLY_SECTION_MEMMAP_HOLES > >>>>> select HAVE_EFFICIENT_UNALIGNED_ACCESS > >>>>> select HAVE_FAST_GUP > >>>>> select HAVE_FTRACE_MCOUNT_RECORD > >>>>> diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h > >>>>> index 75ddfe671393..fcbef3eec4b2 100644 > >>>>> --- a/arch/arm64/include/asm/page.h > >>>>> +++ b/arch/arm64/include/asm/page.h > >>>>> @@ -37,7 +37,6 @@ void copy_highpage(struct page *to, struct page *from); > >>>>> > >>>>> typedef struct page *pgtable_t; > >>>>> > >>>>> -int pfn_valid(unsigned long pfn); > >>>>> int pfn_is_map_memory(unsigned long pfn); > >>>>> > >>>>> #include <asm/memory.h> > >>>>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > >>>>> index f431b38d0837..5731a11550d8 100644 > >>>>> --- a/arch/arm64/mm/init.c > >>>>> +++ b/arch/arm64/mm/init.c > >>>>> @@ -217,47 +217,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > >>>>> free_area_init(max_zone_pfns); > >>>>> } > >>>>> > >>>>> -int pfn_valid(unsigned long pfn) > >>>>> -{ > >>>>> - phys_addr_t addr = PFN_PHYS(pfn); > >>>>> - > >>>>> - /* > >>>>> - * Ensure the upper PAGE_SHIFT bits are clear in the > >>>>> - * pfn. Else it might lead to false positives when > >>>>> - * some of the upper bits are set, but the lower bits > >>>>> - * match a valid pfn. > >>>>> - */ > >>>>> - if (PHYS_PFN(addr) != pfn) > >>>>> - return 0; > >>>>> - > >>>>> -#ifdef CONFIG_SPARSEMEM > >>>>> -{ > >>>>> - struct mem_section *ms; > >>>>> - > >>>>> - if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > >>>>> - return 0; > >>>>> - > >>>>> - ms = __pfn_to_section(pfn); > >>>>> - if (!valid_section(ms)) > >>>>> - return 0; > >>>>> - > >>>>> - /* > >>>>> - * ZONE_DEVICE memory does not have the memblock entries. > >>>>> - * memblock_is_memory() check for ZONE_DEVICE based > >>>>> - * addresses will always fail. Even the normal hotplugged > >>>>> - * memory will never have MEMBLOCK_NOMAP flag set in their > >>>>> - * memblock entries. Skip memblock search for all non early > >>>>> - * memory sections covering all of hotplug memory including > >>>>> - * both normal and ZONE_DEVICE based. > >>>>> - */ > >>>>> - if (!early_section(ms)) > >>>>> - return pfn_section_valid(ms, pfn); > >>>>> -} > >>>>> -#endif > >>>>> - return memblock_is_memory(addr); > >>>>> -} > >>>>> -EXPORT_SYMBOL(pfn_valid); > >>>>> - > >>>>> int pfn_is_map_memory(unsigned long pfn) > >>>>> { > >>>>> phys_addr_t addr = PFN_PHYS(pfn); > >>>>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > >>>>> index 961f0eeefb62..18bf71665211 100644 > >>>>> --- a/include/linux/mmzone.h > >>>>> +++ b/include/linux/mmzone.h > >>>>> @@ -1421,10 +1421,22 @@ static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn) > >>>>> * > >>>>> * Return: 1 for PFNs that have memory map entries and 0 otherwise > >>>>> */ > >>>>> +bool memblock_is_memory(phys_addr_t addr); > >>>>> + > >>>>> static inline int pfn_valid(unsigned long pfn) > >>>>> { > >>>>> + phys_addr_t addr = PFN_PHYS(pfn); > >>>>> struct mem_section *ms; > >>>>> > >>>>> + /* > >>>>> + * Ensure the upper PAGE_SHIFT bits are clear in the > >>>>> + * pfn. Else it might lead to false positives when > >>>>> + * some of the upper bits are set, but the lower bits > >>>>> + * match a valid pfn. > >>>>> + */ > >>>>> + if (PHYS_PFN(addr) != pfn) > >>>>> + return 0; > >>>>> + > >>>>> if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > >>>>> return 0; > >>>>> ms = __nr_to_section(pfn_to_section_nr(pfn)); > >>>>> @@ -1434,7 +1446,11 @@ static inline int pfn_valid(unsigned long pfn) > >>>>> * Traditionally early sections always returned pfn_valid() for > >>>>> * the entire section-sized span. > >>>>> */ > >>>>> - return early_section(ms) || pfn_section_valid(ms, pfn); > >>>>> + if (early_section(ms)) > >>>>> + return IS_ENABLED(CONFIG_HAVE_EARLY_SECTION_MEMMAP_HOLES) ? > >>>>> + memblock_is_memory(pfn << PAGE_SHIFT) : 1; > >>>>> + > >>>>> + return pfn_section_valid(ms, pfn); > >>>>> } > >>>>> #endif > >>>> > >>>> Hello David/Mike, > >>>> > >>>> Now that pfn_is_map_memory() usage has been decoupled from pfn_valid() and > >>>> SPARSEMEM_VMEMMAP is only available memory model on arm64, wondering if we > >>>> still need this HAVE_EARLY_SECTION_MEMMAP_HOLES proposal ? Please do kindly > >>>> suggest. Thank you. > >>> > >>> Even now arm64 still frees parts of the memory map and pfn_valid() should > >>> be able to tell if a part of a section is freed or not. > >>> > >>> For instance for the following memory configuration > >>> > >>> |<----section---->|<----hole---->|<----section---->| > >>> +--------+--------+--------------+--------+--------+ > >>> | bank 0 | unused | | bank 1 | unused | > >>> +--------+--------+--------------+--------+--------+ > >>> > >>> the memory map corresponding to the "unused" areas is freed, but the generic > >>> pfn_valid() will still return 1 there. > >> > >> But is not free_unused_memmap() return early when CONFIG_SPARSEMEM_VMEMMAP > >> is enabled, which is the only option now on arm64. Then how can memmap have > >> holes (from unused areas) anymore ? Am I missing something here. > > > > Ah, you are right, I missed this detail myself :) > > > > With CONFIG_SPARSEMEM_VMEMMAP as the only memory model for arm64, we can > > simply rid of arm64::pfn_valid() without any changes to the generic > > version. > > Though just moved the pfn bits sanity check into generic pfn_valid(). > I hope this looks okay. > > From 7a63f460bcb6ae171c2081bfad81edd9e8f3b7a0 Mon Sep 17 00:00:00 2001 > From: Anshuman Khandual <anshuman.khandual@xxxxxxx> > Date: Tue, 25 May 2021 10:27:09 +0100 > Subject: [PATCH] arm64/mm: Drop HAVE_ARCH_PFN_VALID > > CONFIG_SPARSEMEM_VMEMMAP is now the only available memory model on arm64 > platforms and free_unused_memmap() would just return without creating any > holes in the memmap mapping. There is no need for any special handling in > pfn_valid() and HAVE_ARCH_PFN_VALID can just be dropped. This also moves > the pfn upper bits sanity check into generic pfn_valid(). > > Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > arch/arm64/Kconfig | 1 - > arch/arm64/include/asm/page.h | 1 - > arch/arm64/mm/init.c | 37 ----------------------------------- > include/linux/mmzone.h | 9 +++++++++ > 4 files changed, 9 insertions(+), 39 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index d7dc8698cf8e..7904728befcc 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -154,7 +154,6 @@ config ARM64 > select HAVE_ARCH_KGDB > select HAVE_ARCH_MMAP_RND_BITS > select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT > - select HAVE_ARCH_PFN_VALID > select HAVE_ARCH_PREL32_RELOCATIONS > select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET > select HAVE_ARCH_SECCOMP_FILTER > diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h > index 75ddfe671393..fcbef3eec4b2 100644 > --- a/arch/arm64/include/asm/page.h > +++ b/arch/arm64/include/asm/page.h > @@ -37,7 +37,6 @@ void copy_highpage(struct page *to, struct page *from); > > typedef struct page *pgtable_t; > > -int pfn_valid(unsigned long pfn); > int pfn_is_map_memory(unsigned long pfn); > > #include <asm/memory.h> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 725aa84f2faa..49019ea0c8a8 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -219,43 +219,6 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > free_area_init(max_zone_pfns); > } > > -int pfn_valid(unsigned long pfn) > -{ > - phys_addr_t addr = PFN_PHYS(pfn); > - struct mem_section *ms; > - > - /* > - * Ensure the upper PAGE_SHIFT bits are clear in the > - * pfn. Else it might lead to false positives when > - * some of the upper bits are set, but the lower bits > - * match a valid pfn. > - */ > - if (PHYS_PFN(addr) != pfn) > - return 0; > - > - if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > - return 0; > - > - ms = __pfn_to_section(pfn); > - if (!valid_section(ms)) > - return 0; > - > - /* > - * ZONE_DEVICE memory does not have the memblock entries. > - * memblock_is_map_memory() check for ZONE_DEVICE based > - * addresses will always fail. Even the normal hotplugged > - * memory will never have MEMBLOCK_NOMAP flag set in their > - * memblock entries. Skip memblock search for all non early > - * memory sections covering all of hotplug memory including > - * both normal and ZONE_DEVICE based. > - */ > - if (!early_section(ms)) > - return pfn_section_valid(ms, pfn); > - > - return memblock_is_memory(addr); > -} > -EXPORT_SYMBOL(pfn_valid); > - > int pfn_is_map_memory(unsigned long pfn) > { > phys_addr_t addr = PFN_PHYS(pfn); > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index a9b263d4cf9d..d0c4fc506fa3 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -1443,6 +1443,15 @@ static inline int pfn_valid(unsigned long pfn) > { > struct mem_section *ms; > > + /* > + * Ensure the upper PAGE_SHIFT bits are clear in the > + * pfn. Else it might lead to false positives when > + * some of the upper bits are set, but the lower bits > + * match a valid pfn. > + */ > + if (PHYS_PFN(PFN_PHYS(pfn)) != pfn) > + return 0; > + > if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS) > return 0; > ms = __nr_to_section(pfn_to_section_nr(pfn)); > -- > 2.20.1 -- Sincerely yours, Mike.
